If you want a real adventure for your meal, get a fishing license. You can dig for clams or oysters. I can't remember the street but there is a road right by the cemetary on your right if you go counter clockwise on the island (towards water) the road is not paved but a regular car can drive on it with no problem. Go towards the end of the road and walk down towards the water. Depending on your timing, if the tide is in, you can just pick up the oysters and clams with your hands and no digging is needed, so easy. Just bring a stick with you to help you flip the rocks over and don't forget your bucket.
There's also great fishing that's really easy, no time at all. The place we went to was by the camping grounds. Go towards the water, the area should be relatively low, however don't fish there. Go towards the mountain/rock areas. There should be a walking path. Once you're up there, there should be another path that takes you closer to the water, if you fish there, you'll be successful catches of rock cod. We were there for about a half hour and caught about 10 rockcods. So delicious! We had it for dinner and the left overs for congee the next morning.